Muffler



L. L. HAAS April 26, 1938.

MUFFLER Filed Dec. 21, 1936 lNVI/V 70E f M,

Patented Apr. 26, 1938 PATENT OFFICE MUFFLER Lucien L. Haas,

falo Pressed Steel Company, Buffalo,

Buffalo, N. Y., assignor to Buf- Application December 2-1, 1936, Serial No. 116,901

7 Claims.

This invention relates to improvementsin mufiiers or silencers for use in connection with internal combustion engines.

One of the objects of this invention is to provide a mufller of compact and efiicient construction in which the silencing chambers and channels are arranged in a relatively small space; also to provide a muffler having gas and sound wave conducting channels or passages of improved or simplified construction; also to provide a muliler with a shell having an opening through which gases and sound waves may pass and having secured thereto a channel-shaped member through which sound waves may pass from said opening to a sound deadening chamber.

Other objects of the invention will appear from the following description and claims.

In the accompanying drawing:

Fig. 1 is a central sectional view of a portion of mufiler embodying this invention.

Fig. 2 is a similar view showing the remaining portion of the mufiier.

Fig. 3 is a fragmentary sectional view of the mufiler approximately on line 3-3, Fig. 4.

Fig. 4 is a transverse section thereof, on line l4, Fig. 1.

The muffler may be provided with an enclosing casing or housing of any suitable or usual construction, that shown including an outer shell I, a head 8 at one end thereof provided with an opening to receive gases from an exhaust pipe of an engine and this head may, if desired, be provided with an integral tubular outwardly extending duct 9 to which the end of the exhaust pipe may be secured. At the other end of the outer shell, a head 10 is provided having a tubular part or duct l I to which a tail pipe may be connected. Any other means for forming the enclosing casing or housing of the muffler may be provided.

The muflier illustrated in the accompanying drawing includes within its housing a shell or cylindrical member M which may receive gases and sound waves in any suitable manner, and which is spaced from the outer shell of the muffler so as to form one or more sound deadening chambers, two such chambers and It being provided in the construction illustrated, which are separated from each other by an annular baflle or transverse partition l'l. The tubular member or shell M may be mounted in the muilier in any suitable or desired manner to receive gases and sound waves, and in the particular construction illustrated by way of example, the shell 14 is mounted upon an inner shell l8 provided with perforations l9 of any suitable or desired form.

The ends of the inner shell l9 may be connected with the heads 8 and ID in any suitable manner, for example, by means of collars or sleeves 20, portions of which are telescoped into the inner shell l8 and other portions of which are secured to the heads 8 and H1 in any suitable manner. For example, these sleeves may be welded to the interior of the ducts 9 and l l. The inner shell IB is slidably mounted on the sleeves by means of the telescopic connections to permit expansion and contraction of this shell relatively to the housing of the muiller. The intermediate shell M is supported on the inner shell 18 by means of a series of baffles or transverse partitions 22 which also divide the space between the inner and intermediate shells into a series of chambers 24, 25, 26 and 21. The chambers 25 and 26 serve as high frequency resonance chambers to eliminate certain sounds from the exhaust and the chambers 24 and 21 are connected with the outer chambers l5 and I6. Mufflers of the general construction thus far described have heretofore been used and do not of themselves constitute a part of this invention.

It has been found desirable to provide restricted channels or bottle necks to carry sound waves and pressure pulsations or gases into the larger outer chambers of a mufller and in accordance with this invention, I provide such passages or bottle necks on the outer surface of the intermediate shell in such a manner that the channels are substantially coextensive with all or parts of chambers which they connect. For example, one or more channel-shaped members may be secured on the intermediate shell so as to extend lengthwise thereof and form therewith a tubular passage. In the construction illustrated, substantially trough or channel-shaped members 30 are provided having flanges 3| at their edges which may be welded or otherwise secured to the shell M, a series of spot-welds 32 being shown for that purpose. In order to transmit gases and sound waves into the channels 30, I provide holes or openings 33 in the shell Hi, the holes being pref erably so located as to discharge the sound waves and gases into one end of the channelshaped members 3*]. Preferably the channelshaped members are provided adjacent to the holes or openings 33 with end walls 34 which extend into contact with the shell [4. The flange 3| of each channel-shaped member, consequently, also extends around the end portion 34, so that the channel-shaped members 30 can be securely fastened to the shell M. In the construction shown, the holes or openings 33 are formed adjacent to the inner ends of the intermediate chambers 24 and 2'! so as to provide for channels 30 of considerable length. The location of the holes 33, however, depends upon the lengths of the channels or bottle necks which may be desired, and if shorter channel-shaped members 30 are desired, the holes 33 will be located near to the outer ends of the chambers 24 and 21.

The construction described lends itself readily to the design of mufilers to counteract a great variety of diiferent frequencies of sound waves. For example, the location of the bafile I! may be varied according to the particular sound waves which the muffler is designed to reduce or eliminate. Consequently, the two chambers l5 and I6 may be made of unequal lengths by positioning the bafile it at different distances from the heads 8 and Ill, so that the chambers l5 and I6 may serve to counteract different frequencies. In addition to positioning the partition or bafiie H to vary the length of the resonance chambers l5 and it, the lengths of the channels 39 may also be varied, each to cooperate with its resonance chamber. Thus by proportioning the lengths of the chambers l 5 and l E and of the bottle necks or channels 3il connecting therewith the mufiler can be readily designed to eliminate a variety of different frequencies of sound waves.

In the operation of the mufller, some of the sound waves and gases entering into the inner shell 68 will pass through the apertures or perforations ill in this shell into the intermediate chambers 24, 25, 25 and 21, and some of the gases and sound waves entering into the chambers 24 and 2? will further pass through the channels or bottle necks 3i) into the outer resonance chambers l5 and I6 and then back through the channels or bottle necks and through the chambers 2 and 2'! and perforations 19 into the inner shell. While the mulller is mainly designed so that the sound waves returning to the inner shell from the outer resonance chambers I 5 and I 6 will be out of phase with the sound waves in the inner shell l8 and thus destroy sound by destructive interference, yet the muffler described will also have a similar action upon the gas pressure pulsations in that during a gas pressure peak, gases will flow through the perforations l9 and into chamber 24 or 21 and produce increased pressures and flow of gases in the channels 30 and the chamber l5 or l6. During the succeeding low pressure period, some of the gases stored in these chambers and passages will return to the inner shell and raise the pressure therein during the low pressure period, so as to flatten out or level 01f the pulsations in this shell and thus produce a fairly uniform rate of flow through the balance of. the inner shell and tail pipe.

The construction described has the advantage of making it possible to obtain the desired silencing eifects in a relatively short muiller. For example, in mufflers, such as shown in application No. 723,735 filed jointly by R. J. MacKenzie and myself, the channels or bottle necks are produced in such a manner that they extend beyond the ends of the inner chambers with which they connect. Consequently, such mufflers have to be made of suificient length to include the length of such channel or channels. If, however, the motor vehicle in which the mufller is to be used is of such construction as to necessitate a shorter mufiler, then my construction is desirable in that the channels or bottle necks 30 are superposed or approximately co-extensive with the chambers 24 and 21, so that these channels do not add to the length of the mufiler.

While the channels 30 are shown as extending towards the ends of the mufiler on the exteriors of the chambers 24 and 27, it will be obvious that they can be turned end for end and extend toward the bafile I! on the exteriors of the chambers 25 and 26.

I claim as my invention:

1. In a muffier having a housing and a shell arranged therein which receives gases and sound waves and which has an opening, at least a por tion of said shell being spaced from said housing to form a chamber, the combination therewith of a channel-shaped member having edge portions extending lengthwise of said shell secured to said shell, said channel-shaped member extending over said opening to form a passage for gases and sound waves connecting said opening and said chamber.

2. In a mufller having a housing and a shell arranged therein which receives gases and sound waves and which has an opening, at least a portion of said shell being spaced from said housing to form a chamber, the combination therewith of a channel-shaped member having edge portions extending lengthwise of said shell secured to said shell, said channel-shaped member extending over said opening to form a passage for gases and sound waves connecting said opening and said chamber, an end of said channel-shaped member also extending into contact with said shell to cause gases and sound waves entering said member to flow toward the other end of said channelshaped member. s

3. In a muiiier, the combination with an outer, an intermediate and an inner shell and end heads secured to said outer shell, said inner shell being perforate and being connected with one of said heads to receive exhaust gases, said shells being spaced apart to form between them inner and outer chambers, baffles dividing the space between said inner and intermediate shells into a plurality of inner chambers, the inner chambers formed between said inner and intermediate shells communicating with the interior of said inner shell by means of the perforations, said intermediate shell having an opening in the portion thereof surrounding one of said inner chambers, and a channel-shaped member having edges extending lengthwise of the mufiler secured to said intermediate shell, said member extending about said opening and having the end adjacent to said opening closed, and the other end open, to form with said intermediate shell a passage connecting said last mentioned inner chamber and said outer chamber, to form with said outer chamber a bottle neck resonator chamber.

4. In a mufiler having a housing and a shell arranged therein which receives gases and sound waves and which has an opening, at least a portion of said shell being spaced from said housing to form a chamber, the combination therewith of. a channel-shaped member having flanges at the edges thereof extending lengthwise of the muffler secured to said shell, said member extending over said opening to form a passage for gases and sound waves connecting said opening and said chamber.

5. In a muiiler having a housing and a shell arranged therein which receives gases and sound waves and which has an opening, at least a portion of said shell being spaced from said housing to form a chamber, the combination therewith of an open-sided channel-shaped member having 7 an end wall at one end thereof and open at the opposite end, and a flange formed on the longitudinal edges of the sides and end of said channel-shaped member and secured to said shell over said opening to form a passage from said opening to said chamber.

6. In a mufller, the combination of an outer shell, end heads secured to said shell and each having an opening for gases and sound waves, a perforate inner shell receiving gases from one of said openings, an intermediate shell receiving gases and sound Waves from said inner shell through the perforations thereof and having an opening, said intermediate shell forming with said outer shell a substantially closed outer resonator chamber, and a channel-shaped member secured to said intermediate shell over said opening and through which gases and sound waves pass from said opening into said outer resonator chamber, to form a bottle neck type of resonator chamber.

'7. In a muflier, the combination of an outer shell and end heads having openings through which gases and sound waves may pass, an inner perforate shell for receiving gases from one of said openings, an intermediate shell arranged about said inner shell and supported therefrom by means of a plurality of bafiles forming an inner chamber between said inner and intermediate shells, said intermediate shell also forming an outer resonator chamber with said outer shell and having an opening communicating with said inner chamber, and a channel-shaped member secured to the outer surface of said intermediate shell and extending over said opening and having one end thereof closed and formed of a single piece of metal, the edge portions of which are welded to said shell, said member connecting said inner and outer chambers and forming with said outer chamber a bottle neck type of resonator chamber.

LUCIEN L. HAAS. 

